Monthly Archives: January 2010

Q: I heard grapefruit interacts with certain medications. Is this true?

A: Yes. Unlike other citrus fruits, grapefruit interferes with the metabolism of a few dozen drugs (see partial list below). A chemical component within the fruit prohibits a certain digestive enzyme in the body from breaking down these medications. By continuing to consume grapefruit or grapefruit juice, you decrease the efficacy of the medication you’re on, and the drug itself can build up to dangerously high levels in the blood. Grapefruit should be fully avoided, as its effects wear off very slowly and are still evident 24 hours after consumption. Separating medicine and grapefruit by several hours will not prevent the drug-nutrient interaction. Having grapefruit once accidentally, most likely, will do no harm, but it’s advisable to switch to another type of fruit or fruit juice. The National Institutes of Health recommends not making any sudden diet changes, however, if you’ve always taken your medication with grapefruit. Speak to your doctor first, as your body may be accustomed to a certain level of the drug in your blood.

Avoid grapefruit and grapefruit products when taking the following:

The high blood pressure/angina drugs Plendil and Procardia/Adalat

The cholesterol-lowering agents Zocor, Lipitor and Mevacor

The immunosuppressant medications Sandimmune and Rapamune

The anti-anxiety/anti-insomnia drugs Valium, Halcion and Versed

The neurological medications BuSpar, Zoloft and Tegretol

Note: This is not a complete list of medications that interact with grapefruit. Always check with your physician and/or pharmacist.

A: The sale of nutrient supplements is a billion dollar a year business. But whether you’re looking to ward off cancer, lose weight or make up for poor eating habits, you must be careful when taking supplements! In 1994, the U.S. Food & Drug Administration revised government regulation of dietary supplements, which include vitamins, minerals, amino acids, herbs, enzymes and many other substances. The new law determined that it is up to the manufacturer of the supplement to make sure that the product is safe, the label claims are substantiated by solid evidence and that the supplement’s content matches ingredients declared on the packaging. In short, supplements do not need approval from the FDA prior to marketing, nor does the FDA analyze the composition of these products. Manufacturers are required to investigate and alert the FDA of any reports of adverse health events associated with the product.

Supplements are indicated for certain groups of people: people with diagnosed nutrient deficiencies, pregnant women, infants, those who are lactose intolerant, perpetual dieters, those addicted to drugs or alcohol, strict vegetarians, and those suffering or recovering from illness, surgery or injury. While these may be valid reasons to be taking supplements, you should always notify your doctor of any over-the-counter products you’re consuming.

Taking supplements increases your risk of toxicities. High potency single nutrient supplements can cause accidental poisoning that can result in liver damage, shock and possible death. High doses can be very dangerous and labels can sometimes lure you with misleading or unproven claims. Certain nutrients, such as the fat-soluble vitamins A, D, E and K, can build up in your system over time. In fact, intakes of vitamin A just twice the recommended amount, taken over a few years, are associated with osteoporosis, while daily supplements of beta-carotene may increase lung cancer risk in smokers. Always adhere to government-set tolerable upper intake levels, unless your doctor suggests otherwise. (Click here for detailed information on daily recommendations and upper limits for vitamins and minerals, divided by age and gender.)

Supplements can also affect the absorption and metabolism of medicines you take and nutrients in the food you eat. For example, when taken in a pure form, zinc interferes with copper and calcium absorption and calcium hinders magnesium and iron absorption. In addition, the herbal product St. John’s Wort can severely limit the effectiveness of AIDS medications and is not recommended when simultaneously taking an antidepressant from the SSRI family. Clearly, taking multiple over-the-counter supplements increases your chance for harmful food-drug and drug-drug interactions.

My best advice is to try and get all your nutrients from food! Taking a multivitamin can help “cover your bases,” but any amount of certain vitamins or minerals consumed in excess of what your body needs will generally be excreted. While a banana and a tablet may both contain potassium, the fruit provides a balanced assortment of nutrients, fiber and phytochemicals (beneficial, active plant compounds) that can temper the effects of the mineral.

While fiber does not provide energy, it has many other beneficial effects:

1. Lowers blood cholesterol: Soluble fiber reduces cholesterol and the risk of heart disease by several mechanisms. (Note: This is why General Mills is able to claim that eating whole grain oat Cheerios can help lower your cholesterol.)

3. Assists blood glucose control: Soluble fiber slows the absorption of glucose from the intestine into the blood stream, thereby preventing a spike (and crash) in blood glucose after a meal. This can lower the risk of type 2 diabetes.

5. May defend against colon and rectal cancer: Scientific studies are mixed, but insoluble fiber speeds up the removal of cancer-causing agents from the colon, while resident bacteria in the colon ferment soluble fiber, producing a beneficial compound that may help colon cells resist injury.

Recommended Intake: Since most fiber-rich foods supply a mixture of soluble and insoluble fiber, recommendations are given without regard to type. The American Dietetic Association suggests 20 – 35 grams of fiber daily, which is about twice the average intake. That said, don’t overload on fiber and make sure to increase fluid consumption as you gradually increase fiber intake.

Fruits, vegetables, whole grains and beans are among the best sources of fiber! Also, remember that fiber supplements are not necessarily substitutes for whole, fiber-rich foods.

Check the nutrition facts on the back of products to find out how much fiber is in one serving! Here are some examples:

A: No! You should always aim to eat breakfast whether or not you’re trying to lose weight! Breakfast gives you the fuel to start your day off right. During the night, your body goes 8-12 hours without food, so breakfast replenishes dwindling blood sugar reserves. People who do not eat breakfast feel more tired, irritable and less focused.

Eating breakfast revs up your metabolism. When you don’t eat for long periods of time, your cells are hungry and your body naturally slows down your metabolism to store energy and burn only what’s absolutely necessary. If you want to lose weight, however, you want to speed up your metabolism. Another way to boost your metabolism is by exercising!

Evidence shows that eating breakfast can reduce food intake throughout the entire day. You’re more likely to snack on sweet and fatty foods and overload at lunchtime if you skimp on breakfast. In fact, people who miss this meal are more often overweight than breakfast eaters.

Additionally, research has shown that children and young adults who skip breakfast have a significantly lower intake of most vitamins and minerals when compared to those who consume breakfast.

Breakfast is arguably the easiest meal of the day to prepare, so even if you have to eat it on the run, that’s OK! Pack a small bag of trail mix or a piece of fruit to eat when you get to school or work.

A: Yes! A quick look at the nutrition facts tells us there is a big difference between butter and margarine! The debate focuses on the types of fat found in these products and stick butter has the most saturated fat per tablespoon (7g), giving it the most unhealthy characteristics.

When it comes to eating a heart healthy diet, you want to minimize intake of artery-clogging trans-fat and saturated fat, both of which can raise your LDL (bad) cholesterol level. Keep trans-fat consumption to a minimum and saturated fat to less than 10% of daily calories. (That’s 20g saturated fat for a daily 2,000 calorie diet!)

Years ago, hard margarines were made with unhealthy hydrogenated oils. Hydrogenation is the process of taking unsaturated (healthier) fats and adding hydrogen atoms to obtain characteristics of a saturated fat. For example, hydrogenated oils are firmer and easier to spread, but this causes the loss of health benefits associated with unsaturated fats. Trans-fatty acids also form during hydrogenation and pose a double risk to heart health by raising LDL (bad) cholesterol AND lowering HDL (good) cholesterol. Thanks to better technology, soft margarines and spreads can now be made from a blend of unhydrogenated oils, such as soybean and canola oils, which are mostly unsaturated and, therefore, more heart healthy than butter.

While whipped butter has less saturated fat per tablespoon that stick butter (see below), soft margarine and spreads are clearly the way to go to save on calories and saturated fat grams! The bottom line? Check the ingredient list to make sure the product is not made with partially hydrogenated oils and look for spreads that are trans-fat free and low in saturated fat!

A: Cold sores, or fever blisters, are caused by the herpes simplex virus. While the virus cannot be cured, cold sores can be treated. Along with avoiding triggers, such as excessive sun exposure, stress and colds, there is some evidence that nutrition plays a role in cold sore prevention.

Studies have shown that topical zinc oxide cream shortens the duration of a herpes outbreak, while oral zinc tablets are associated with reduced frequency and duration of flare-ups. In addition, lemon balm may speed up the healing process, but has no impact on prevention.

Lysine and arginine are amino acids – building blocks of proteins – that have been implicated in cold sore management. Lysine has been shown to inhibit normal replication of the virus, thereby lessening outbreak duration, while arginine seems to promote growth of the virus. Thirty years ago, a multi-centered study gave patients 1,200mg daily oral lysine doses, which appeared to accelerate recovery from infection and suppress recurrence of outbreaks (Griffith et al., 1978). It is difficult, however, to make a recommendation for daily lysine supplementation, because more recent studies have supplied participants with anywhere from 500 to 3,000mg lysine per day and long-term research is inconclusive.

In short, there does seem to be some consensus that diets high in lysine and low in arginine are beneficial for those who suffer from cold sores. See below for a list of potentially beneficial foods and a list of foods to avoid. If you find that limiting certain foods makes no impact on your cold sore symptoms, add those items back into your diet! Very restrictive diets may not supply adequate amounts of certain necessary nutrients.

Beneficial: Foods high in lysine & low in arginine

Dairy (e.g. milk, cheese, yogurt)

Meat, chicken, fish

Mango, apricots, pears, apples, figs

Beets

Papaya

Avocado

Tomato, tomato juice, tomato paste

Foods to avoid: High in arginine & low in lysine

Coconut

Grape juice, orange juice

Rice

Peanut butter

Chocolate

Caffeine

Puffed wheat, corn, rice and oats

Nuts

Onions

Oatmeal

Plantains

Yams

Tahini

Lastly, in the midst of an outbreak, it may be best to avoid acidic foods, such as soda, citrus fruits, tomatoes, vinegar and alcohol, which may exacerbate the blisters.

Q: How much calcium should I be getting and what are the best sources?

A: Adults (19-50 years old) should consume a minimum of 1,000mg calcium daily and adults 51+ years are recommended to get at least 1,200mg. Intakes for children and adolescents should be a little higher, since they are still accumulating bone mass. Aim to meet food pyramid recommendations and you’ll be well on your way to reaching calcium guidelines.

Most of us know that calcium is an integral part of bone structure, but this mineral does much more than that! Calcium plays an important role in maintaining normal blood pressure, blood clotting, muscle contraction and the transmission of nerve signals. The body tightly regulates blood calcium levels, and when intake is inadequate, the body draws on calcium stores in bones and teeth.

It’s important for kids and teens to get enough calcium, so that they are able to achieve their height potential and an optimal bone mass, which is reached by age 30. After age 40 or so, bone density inevitably begins to decline and a person with insufficient calcium stores is at risk for osteoporosis. Fortunately, bone loss can be slowed by a diet adequate in calcium and with regular physical activity!

It’s always best to obtain vitamins and minerals from food sources, rather than by taking a supplement. In fact, calcium supplements may be less effective at building strong bones, which may be due to the fact that other micronutrients found in a well-balanced diet – including vitamin D, vitamin K, magnesium and phosphorus – all play necessary roles in bone metabolism.

Some of the best sources of calcium come from the dairy group, but there are great vegetarian sources as well! Besides milk, yogurt and cheese, broccoli, collard greens, cauliflower, brussels sprouts, bok choy and kale are also excellent sources of calcium. Note that spinach, rhubarb and Swiss chard appear equal to milk in calcium content, but they actually provide little calcium to the body, because these foods also contain compounds that prevent absorption of the mineral.

So, what if you don’t drink milk? If you’re lactose intolerant, lower-lactose or lactose-free products are available, as well as enzymes that can be taken orally or added to the milk. Calcium-fortified juice and soy beverages provide calcium as well, but they may not provide other important nutrients found in dairy products.